Renault says it needs to focus on the drivability of its power unit before it can say it is truly getting 100% out of its new V6 turbo and energy recovery system.

Renault has been hit by a number of issues while testing its new power unit but is confident it is making progress this week at the final test in Bahrain. Daniel Ricciardo's improved performance on Friday in the Red Bull was the first tangible evidence of the step forward, but head of trackside operations Remi Taffin says the engine is still not delivering exactly in the way Renault wants.

"I would say [it was running] cleaner [than before], but not 100%," he said. "If I was driving the car, to be completely fair, I would be complaining. We know exactly where we have to work on and there is still quite a lot of room to play with. It's our objective to try to get to the level of the V8, which we knew was very good in terms of drivability, so we've got a target and we have to get there.

"It's definitely software related. It's how we run the different components and, for example, the internal combustion engine - the V6 turbo - and the electrical machine. Individually they work fine but we are making them all work together, but we still have a lot to do.

"You could argue we were at full power but we were still not happy with drivability. Any corners that you can't get the right exit out of could cost a tenth or two, so it's very difficult to say."

Friday also marked the deadline for the first stage of engine homologation with the FIA. The F1 Strategy Group discussed and rejected the idea of extending the deadline, but Taffin said Renault did not ask for an extension and would manage without it.

"Anything you can do within three months is a help, whether it's to do with performance or reliability, it would help. It's a no-brainer. But I don't think we needed that time because we've gone through and we have an engine with the FIA and that's how we are going to run in Melbourne."

Under the regulations changes can be made to the engines for reliability, cost saving and safety purposes. Taffin said Renault would most likely use this rule just as it and all the other teams did under the V8 engine freeze in previous years.

"We are not planning to have any problems with our power unit, but we have to be honest and I'm sure we will meet some problems through the year and we will use this rule for sure. As we have done for years, it has always been like this [under previous engine freezes]."